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Chapter 21 Musical Sounds Noise Versus Music Doc Cam - Figure 20.1 Wav Win - Noise and Wave Forms Three characteristics of a musical tone: Pitch Loudness Quality 1. PITCH The pitch of a sound is related to its frequency. The exact relationship is complex.

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chapter 21

Chapter 21

Musical Sounds

noise versus music
Noise Versus Music

Doc Cam - Figure 20.1

Wav Win - Noise and Wave Forms

Three characteristics of a musical tone:

Pitch

Loudness

Quality

1 pitch
1. PITCH
  • The pitch of a sound is related to its frequency.
  • The exact relationship is complex.
  • For simple sounds, the greater the frequency

the greater the pitch.

  • For complex sounds, pitch assignment is

an involved psychological process.

slide5

Change pitch by altering the vibrating source.

  • Response to high pitch usually declines

with age.

2 sound intensity and loudness
2. SOUND INTENSITY AND LOUDNESS
  • Intensity -

refers to pressure variations

  • Intensity is directly proportional to the pressure amplitude squared.
  • The human ear can hear intensities over a tremendously large range.
  • Loudness depends on intensity in a complicated way. It does not increase as rapidly as intensity.
loudness
Loudness
  • b = 10 log(I/Io)
  • Measured in decibels (db)
  • Loudness depends on our sensitivity to different frequencies.
  • Demo – Sound Meter
common sound intensities
Common Sound Intensities

Intensity, I (W/m2)

Source of Sound

Sound Level, b (db)

Threshold of Hearing

I0 = 10-12

0

10-11

Rustle of Leaves

10

Whisper

10-10

20

Quiet Radio in Home

10-8

40

10-6

Conversation in Home

60

10-5

70

Busy Street Traffic

10-3

Riveter

90

10-1

Disco Music Amplified

110

1

Air-raid Siren, Nearby

120

102

Jet, 30 m Away

140

3 quality
3. QUALITY
  • Quality is the same thing as timbre.

pronounced TAM-burr (French)

  • It is easy to distinguish two different instruments playing the same note.
  • The quality of a musical sound depends on the number of partial tones and their relative intensities.
slide10
The lowest frequency associated with a musical note is called the fundamental frequency.
  • Any partial that is a whole number multiple of the fundamental frequency is called a harmonic.
  • Overtones are consecutively numbered partials of frequency higher than the fundamental.
slide11
Harmonics

Next Slide

slide12

Vibrating String

First Overtone or

Second Harmonic

Second Overtone or

Third Harmonic

Fundamental or

First Harmonic

Closed Organ Pipe

Fundamental or

First Harmonic

Second Overtone or

Fifth Harmonic

First Overtone or

Third Harmonic

Open Organ Pipe

Fundamental or

First Harmonic

Second Overtone or

Third Harmonic

First Overtone or

Second Harmonic

slide13
URL - Animated Vibrating String
  • Demo - Harmonics on a Guitar
  • Demo - Organ Pipe
  • URL - Animated Organ Pipe
slide14
Demo - Downing’s Resonance Bottle
  • Demo - Speak with different gas in airway
  • Demo - Soda Straw Reed

and Train Whistle

  • The brain can fill in missing lower harmonics that small speakers cannot create.
4 musical instruments
4. MUSICAL INSTRUMENTS
  • 3 basic types

stringed, air column, and percussion

  • Because of energy loss, string sections in orchestras are generally larger.
  • Electronic
5 fourier analysis
5. FOURIER ANALYSIS
  • The eardrum responds to a sum of all the waves arriving at a particular instant. Yet the individual sounds are “heard.”
  • Any waveform is composed of an infinite number of simple sine waves of various frequencies and amplitudes.
slide17

Fourier Analysis - URL

  • Oboe and Clarinet
  • Composite Wave
  • URL – Simultaneous Multiple Harmonics
6 compact discs
6. COMPACT DISCS
  • Phonograph players give analog signals.
  • Analog to Digital
  • Digital signal is in binary code.
  • CD has flats and pits and is sampled 44,100 times per second.
  • Laser Disk
the quality of a musical note can be changed by simply playing the note on a different instrument
The quality of a musical note can be changed by simply playing the note on a different instrument.

(a) True

(b) False

(a) True

slide21
If the note middle C has a pitch of 262 vibrations per second, its second overtone on a vibrating string has a frequency of

(a) 131 vibrations per second

(b) 262 vibrations per second

(c) 524 vibrations per second

(d) 786 vibrations per second

(e) none of the above

(d) 786 vibrations per second

the three characteristics of a musical tone are loudness quality and timbre
The three characteristics of a musical tone are loudness, quality, and timbre.

(a) True

(b) False

(b) False

slide23

The wavelength of the fundamental vibration on a l m long string is half as long as the wavelength of the fundamental vibration in a closed organ pipe of l m length.

(a) True

(b) False

(a) True

the ear can fourier analyze a sound wave but the eye cannot fourier analyze a light wave
The ear can “Fourier analyze” a sound wave, but the eye cannot “Fourier analyze” a light wave.

(a) True

(b) False

(a) True

slide25
If the fundamental frequency of a violin string is 440 Hz, what is the frequency in Hz of the first overtone?

(a) 1320

(b) 880

(c) 440

(b) 880